1. Field of Art
The present invention relates generally to a system and method for retrofitting a roof envelope of a building. More particularly, the present invention relates to a system and method for installing a new metal roof over an existing metal roof. Still more particularly, the present invention relates to a roll formed metal roof subframe system which enables installation of a span of new metal roof decking panels over a span of existing metal roof decking panels.
2. Description of Related Art
Metal roof decking is a building envelope system made from metal decking panels or sections. Each metal decking panel is secured by fasteners to the support structure (typically made of steel) of the building on which the roof is located Metal roof decking is inherently strong and lightweight, and thus offers several advantages over other types of roofing (i.e., asphalt shingles, etc.), such as increased durability, energy efficiency, resistance to weather damage, and ease of installation, as well as being comparatively economical and having low maintenance requirements. Also, metal roof decking may be designed for use with pitched, flat, or arched construction, and may be applied to nearly all types of buildings.
Standing seam metal roofs are also popular on virtually all types of buildings due to their weather-tightness, durability, and flexible design. Additionally, standing seam metal roofs are more energy efficient and cost effective than many non-metal counterparts, and have an additional desired characteristic of allowing for thermal movement within the roof system.
Metal roof decking products have a number of shapes, materials, and aesthetic variations that can be used in constructing roof decking for buildings. One common type of metal roof decking is known as a fluted, or ribbed, roof decking. Ribbed metal roof decking includes a plurality of ribbed metal roof decking panels, each panel characterized by a sequence of alternating upper and lower surfaces that extend the length of the panel. The upper surfaces, or ribs, are found substantially in an upper plane, and are substantially parallel to each other. Likewise, the lower surfaces, or valleys, are found substantially in a lower plane, one that is generally parallel to and spaced vertically apart from the upper plane. The upper and lower surfaces are connected by a series of vertical or sloped walls which also extend the length of the panel. The upper, lower and vertical or sloped walls define flutes, or channels. When installed to form metal roof decking, the ribbed metal roof decking panels typically overlap one another, and span over and are secured by fasteners to underlying support structures, sometimes referred to as purlins. In this configuration, the ribbed metal roof decking panels are connected to form a continuous span to create the roof envelope of a building.
For various reasons, the metal roof decking of a building, in part or whole, may be in need of repair, replacement, upgrade, or a general retrofit. Due to the lightweight qualities of some metal roof decking, an existing roof may be retrofit by installing a system of subframes over the original roof decking, and securing the new roof decking to the subframe system. The use of subframe systems in this manner provides additional support and points of attachment for the new metal roof decking panels. In some instances, however, conventional subframe systems cannot be used to transition from an older roof configuration in need of retrofit to a new metal roof decking that complies with new construction practices and roof uplift requirements. Additionally, conventional subframe systems may not provide the necessary strength over a long roof span, and may require inefficient production and time-consuming installation processes.
Accordingly, there remains a need for new and improved metal roof subframing systems for use in the retrofit of metal roof decking that address certain of the foregoing difficulties.